Okay, cool. So based on the posts so far, how things are turning out:
1. Saturn C-4 (named "Saturn IV") as the main launch vehicle. 99 tonnes to LEO versus 140 tonnes. Astronautix has the C-4 cost per launch as $58 million, versus $494 million for Saturn V. Can't possibly be correct, surely? I also wonder about the logistics of launching two Saturn IVs so close together - three days if in 185 km orbit, or 30 days in a 270 km orbit, according to Michel Van. Fastest ever turnaround of Saturn V launches was about 60 days.
2. Delay of 6-8 months and an extra cost of $1 billion if NASA goes with EOR? That's according to this. So the first moon landing might takes place in late 1969.
3. Smaller CSM than OTL. Allows for easier conversion to Earth orbit operations (space stations). OTL Block II had endurance of 14 days; Apollo 17 pushed it to the limit with 12 twelve days. Presumably, it's still built with fuel cells providing power, with a solar power version waiting for later.
4. Enlarged LM. Performs LOI. Longer surface stays and the possibility of bring all three men down to the surface. Limits of CSM mean a stay of no more than seven days. Could be modified over its lifetime for greater capability - so it with start out with two-crew and building up to longer stays. Problem is how do you test it - Saturn IB is too small to launch a unmanned version like Apollo 5. Do you do the first test with a manned crew, or do you launch it on a Saturn IV, and waste two-thirds of the payload? Or -- and this might be stretching the finances and engineering too far -- do you use a Saturn IV flight to launch the test LM and a test space station module?
5. So! How I imagine things working prior to the first lunar landing:
July 1966 -- AS-203 (one Saturn IB): tested restart capability of S-IVB. Accident resulted in S-IVB being destroyed about six hours into the flight. Second test approved to ensure S-IVB could restarted after three days (OTL, the S-IVB was approved for use on the Saturn V after just AS-203, despite the premature destruction of the S-IVB).
August 1966 -- AS-204 (one Saturn IB): second test of restart capability of S-IVB. Successful refired after three-day loiter period for arrival of Apollo CSM/LM stack.
October 1966 -- AS-202 (one Saturn IB): second unmanned test of Block I Apollo.
January 1967 -- Apollo 1 fire? Probably happens anyway. Failure of AS-203 and the second test flight needed pushes it back to March/April 1967. If it doesn't happen then we can assume fatal consequences down the line.
November 1967 -- Apollo 4 (one Saturn IV): first test of Saturn IV launch vehicle/Block II CSM heat shield. Problems with the S-IVB don't push it back, problems with S-II does, built by North American Aviation, the same company that built the fault Block I CSM. So it probably flies first around the same time as OTL Apollo 4 did.
January/February 1968 -- Apollo 5 (one Saturn IV): second test of Saturn IV launch vehicle/Block II CSM heat shield. Also a test of how long it takes to prepare for another Saturn IV flight after a previous one. LM test delayed prior to determining no problems Saturn IV. Potential third test cancelled as unnecessary.
May 1968 -- Apollo 6 (one Saturn IV): first unmanned, orbital test of LM. Extra payload capacity opens up interesting possibilities of what could be launched with the LM.
October 1968 -- Apollo 7 (one Saturn IB): first manned, orbital test of Apollo CSM.
December 1968 -- Apollo 8 (two Saturn IBs): Tested rendezvous and docking with Apollo CSM and S-IVB; modified docking mechanism launched with manned Saturn IB to enable CSM to dock with S-IVB without LM, due to delays with Grumman. S-IVB test-firing takes crew to elliptical high Earth orbit. (OTL lunar orbit mission doesn't happen, because the docking needs to be tested.)
Late 1968/Early 1969 -- Manned Soviet Zond flight around the Moon?
March 1969 -- Apollo 9 (one Saturn IB, one Saturn IV): First American spacecraft to deliver manned crew to lunar orbit. Used Saturn IB to launch CSM and Saturn IV to launch S-IVB. Judged necessary to test fully-fueled S-IVB launched on Saturn IV. CSM docked with same mechanism used on Apollo 8, and once checks were all completed, proceeded to moon. Flight also politically important to demonstrate US superiority (Soviets might be the first to fly by the moon, but America was the first to orbit it).
May 1969 -- Apollo 10 (one Saturn IB, one Saturn IV): Manned test of LM in Earth orbit. Completed CSM/LM stack docked with S-IVB for test firing in addition to other LM tests.
July 1969 -- Apollo 11 (two Saturn IVs): "Dress rehearsal" for first manned landing. First launch of two Saturn IVs so close together; CSM/LM docks with S-IVB after just two days. First test of LM in lunar orbit.
November 1969 -- Apollo 12 (two Saturn IVs): First manned lunar landing. Pete Conrad and Alan Bean touch down in Sea of Tranquility on November 20, 1969.
(Of course this timeline is up for debate. I wonder if another test/modified test is needed to have two Saturn IVs launch to orbit before attempting to do it with a lunar orbit flight.)
(Another thought: with so many extra Saturn IBs being launch there might be an incentive to develop an alternate launch vehicle for that size payload (20,000 kg). MOL was cancelled around this time, how quickly could Titan IIIM be converted to launch an Apollo CSM? If they stick to the planned MOL timetable it might be ready to fly for the first Skylab missions (assuming it's exactly the same station.
).)
1. Saturn C-4 (named "Saturn IV") as the main launch vehicle. 99 tonnes to LEO versus 140 tonnes. Astronautix has the C-4 cost per launch as $58 million, versus $494 million for Saturn V. Can't possibly be correct, surely? I also wonder about the logistics of launching two Saturn IVs so close together - three days if in 185 km orbit, or 30 days in a 270 km orbit, according to Michel Van. Fastest ever turnaround of Saturn V launches was about 60 days.
2. Delay of 6-8 months and an extra cost of $1 billion if NASA goes with EOR? That's according to this. So the first moon landing might takes place in late 1969.
3. Smaller CSM than OTL. Allows for easier conversion to Earth orbit operations (space stations). OTL Block II had endurance of 14 days; Apollo 17 pushed it to the limit with 12 twelve days. Presumably, it's still built with fuel cells providing power, with a solar power version waiting for later.
4. Enlarged LM. Performs LOI. Longer surface stays and the possibility of bring all three men down to the surface. Limits of CSM mean a stay of no more than seven days. Could be modified over its lifetime for greater capability - so it with start out with two-crew and building up to longer stays. Problem is how do you test it - Saturn IB is too small to launch a unmanned version like Apollo 5. Do you do the first test with a manned crew, or do you launch it on a Saturn IV, and waste two-thirds of the payload? Or -- and this might be stretching the finances and engineering too far -- do you use a Saturn IV flight to launch the test LM and a test space station module?
5. So! How I imagine things working prior to the first lunar landing:
July 1966 -- AS-203 (one Saturn IB): tested restart capability of S-IVB. Accident resulted in S-IVB being destroyed about six hours into the flight. Second test approved to ensure S-IVB could restarted after three days (OTL, the S-IVB was approved for use on the Saturn V after just AS-203, despite the premature destruction of the S-IVB).
August 1966 -- AS-204 (one Saturn IB): second test of restart capability of S-IVB. Successful refired after three-day loiter period for arrival of Apollo CSM/LM stack.
October 1966 -- AS-202 (one Saturn IB): second unmanned test of Block I Apollo.
January 1967 -- Apollo 1 fire? Probably happens anyway. Failure of AS-203 and the second test flight needed pushes it back to March/April 1967. If it doesn't happen then we can assume fatal consequences down the line.
November 1967 -- Apollo 4 (one Saturn IV): first test of Saturn IV launch vehicle/Block II CSM heat shield. Problems with the S-IVB don't push it back, problems with S-II does, built by North American Aviation, the same company that built the fault Block I CSM. So it probably flies first around the same time as OTL Apollo 4 did.
January/February 1968 -- Apollo 5 (one Saturn IV): second test of Saturn IV launch vehicle/Block II CSM heat shield. Also a test of how long it takes to prepare for another Saturn IV flight after a previous one. LM test delayed prior to determining no problems Saturn IV. Potential third test cancelled as unnecessary.
May 1968 -- Apollo 6 (one Saturn IV): first unmanned, orbital test of LM. Extra payload capacity opens up interesting possibilities of what could be launched with the LM.
October 1968 -- Apollo 7 (one Saturn IB): first manned, orbital test of Apollo CSM.
December 1968 -- Apollo 8 (two Saturn IBs): Tested rendezvous and docking with Apollo CSM and S-IVB; modified docking mechanism launched with manned Saturn IB to enable CSM to dock with S-IVB without LM, due to delays with Grumman. S-IVB test-firing takes crew to elliptical high Earth orbit. (OTL lunar orbit mission doesn't happen, because the docking needs to be tested.)
Late 1968/Early 1969 -- Manned Soviet Zond flight around the Moon?
March 1969 -- Apollo 9 (one Saturn IB, one Saturn IV): First American spacecraft to deliver manned crew to lunar orbit. Used Saturn IB to launch CSM and Saturn IV to launch S-IVB. Judged necessary to test fully-fueled S-IVB launched on Saturn IV. CSM docked with same mechanism used on Apollo 8, and once checks were all completed, proceeded to moon. Flight also politically important to demonstrate US superiority (Soviets might be the first to fly by the moon, but America was the first to orbit it).
May 1969 -- Apollo 10 (one Saturn IB, one Saturn IV): Manned test of LM in Earth orbit. Completed CSM/LM stack docked with S-IVB for test firing in addition to other LM tests.
July 1969 -- Apollo 11 (two Saturn IVs): "Dress rehearsal" for first manned landing. First launch of two Saturn IVs so close together; CSM/LM docks with S-IVB after just two days. First test of LM in lunar orbit.
November 1969 -- Apollo 12 (two Saturn IVs): First manned lunar landing. Pete Conrad and Alan Bean touch down in Sea of Tranquility on November 20, 1969.
(Of course this timeline is up for debate. I wonder if another test/modified test is needed to have two Saturn IVs launch to orbit before attempting to do it with a lunar orbit flight.)
(Another thought: with so many extra Saturn IBs being launch there might be an incentive to develop an alternate launch vehicle for that size payload (20,000 kg). MOL was cancelled around this time, how quickly could Titan IIIM be converted to launch an Apollo CSM? If they stick to the planned MOL timetable it might be ready to fly for the first Skylab missions (assuming it's exactly the same station.
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